This invention relates to rods for toy construction sets, and particularly to rods which are easier to remove and are less likely to be broken while being removed.
Toy construction sets having spaced apart joint elements which are interconnected with elongate rods are well known in the prior art. Such construction sets are shown, for example, in U.S. Pat. No. 4,129,975 where hollow spherical balls having a plurality of planar facets containing joint openings are interconnected by rods having deflectable clips at each end that snap fit into the joint element openings. While such construction sets have considerable play value and allow construction of a wide range of complex structures, they have a couple of shortcomings. First, it is difficult to remove a rod that is connected at both of its ends to joint elements that are embedded in a structure without distorting the structure to the point where it is likely to be torn apart or even be damaged. In addition, when the rods are being removed from a joint element, especially by younger children, it is common to rotate them relative to the joint element which creates a bending moment in the clip which causes it to break. While this problem can be alleviated to some degree by making the rods out of high strength plastics, doing so increase the costs of rods substantially.
The subject invention overcomes the shortcomings of the prior art rods by separating the rods into three separate pieces. An elongate strut which extends between opposed joint elements comprises the body of the rod. The strut has cavities formed in each end which slidably receive clips that connect the rod to the joint elements. Each clip has opposed spaced-apart fingers that are deflectable inwardly toward one another and have outwardly facing catches at their extremities. The clip is moveable in the cavity between an open position, where the clip is located completely in the cavity, and a closed position, where the clip extends through a joint opening, and the joint element is clamped between the catch and the end of the strut.
In a preferred embodiment of the invention, the strut has a slot extending through each end which intersects the cavity. The fingers of the clips have outwardly facing protrusions which are aligned with the catches, and both the protrusions and the catches fit into the slots. The protrusions assist the user in moving the clip between its open and closed positions and in releasing the catches from the joint element when it is desired to remove a rod.
In a preferred embodiment of the invention, the clip has a hook located at its end which fits into a recess in the wall of the cavity to prevent the clip from being moved out of the cavity beyond the closed position. The hook and recess also provide detents which prevent movement of the clip from either its open or closed position without exertion of a specified force.
Also in a preferred embodiment of the invention the lips on the catches, which engage the joint element when the clip is in its closed position, have chamfered side and front edges. This allows some rotary movement of the clip relative to the joint element when the clip is being removed from the joint element and thus reduces the bending moment in the clip which causes breakage.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.